I'm curious what the use-case of this extension is? Other sites/applications aren't going to be using this custom protocol handler, and if it's just for my own browser then I'm going to be creating containers and then setting "always open site in this container" and Firefox will always open that site in a specific container. What are you using this for?
> Other sites/applications aren't going to be using this custom protocol handler
I have my own xdg-open in the PATH which supersedes the /usr/bin one (I believe there actually is a plugin mechanism for xdg-open but I found it easier to just create my own binary than learn their tomfoolery), and with that in mind, I'm able to make any URL routing decisions I'd like via that
> then setting "always open site in this container"
... which won't work for multi-tenant sites like console.aws.amazon.com or portal.azure.com which use cookies or other such nonsense to determine who you are currently logged in as. That's actually true of Google and Microsoft, too, although I have less day-to-day experience with that. I am, of course, aware of the user switcher built into both AWS and Azure consoles, but it's not the same as having a giant red themed container for production accounts versus green for QA ones
As for your specific question, I also use aws-vault to cook federated login URLs for the console because my experience of working with AWS SSO and Okta is some ... it's a lot of clicking ... versus letting aws-vault build the federated signin URL and then launching it into the container named according to its AccountID (so it's easy to programatically dispatch them)
